This research purposed to study 1) the level of knowledge and understanding of Primary good manufacturing practice (GMP), including basic knowledge of Primary GMP, sanitation and hygienic operations, and safe food production process; 2) the level of management controls for Primary GMP; and 3) capabilities for explaining the variance in levels of knowledge of Primary GMP. The research sample included 44 persons in the Bangchang Housewife Group, Samut Songkhram Province. A questionnaire served as the research instrument for collecting data from the samples. Descriptive statistics used in the research consisted of mean, standard deviations, percentages, t-tests and correlation coefficients using multiple regression analyses. The study proved that the overall level of knowledge of Primary GMP was fair, which reflected a moderate level of understanding. Consequently, the mean and standard deviation statistics equated to 3.13 and 0.40 ( = 3.13, SD = 0.40). Statistically, the results indicated a positive relationship between the premise-based audit and reputation. No negative indicators for public relations, housewife groups need, and product presentation were found, with a statistical significance level of 0.05. According to the results, basic knowledge of Primary GMP and safe food production processes can explain the Bangchang Housewife Groups satisfaction with the Primary GMP. This studys findings contributed new knowledge on Primary GMP in different areas and helped raise product value.